Except, of course, that they don't, because they hide behind the anonymity of a brainless moniker when posting their graffiti on social media.

They know who the star is: the star doesn't know them. That's the social media deal.

For the print and broadcast media, Twitter has become an essential news feed. The tabloids and celeb magazines whip up the irritation, and occasional real upset, caused by the trolls into 'Star's Agony' headlines.

Increasingly, in come the police to investigate, arrest and provide evidence for the Crown Prosecution Service to bring charges. 'Troll Unmasked': 'Troll Charged': 'Troll Jailed', run the next tabloid headlines. Everyone is happy. Old media feed off new media in their battle for survival in the changing media age.

No matter that, in their desperation to run celebrity stories, newspapers and magazines are giving the skulking trolls the importance they crave.

The police are increasingly being asked to act in areas which the overriding rights of freedom of speech would have previously rendered no-go areas for law enforcement. It is an unintended consequence of social media that, while connecting the world more closely, it is imperilling our hardest won right of communication.

As PR professionals we advise our clients to go on Twitter for a variety of reasons. The medium can maximise commercial values when an individual brings to the negotiating table of a potential sponsor or partner a following of, say, half a million.

It can contribute to the building of reputation through the promotion of positive profile and the fast and directly attributable rebuttal of negativity.

But it does come with the price of exposing your brand to adverse and illiterate comment. That's democracy.

In Twitter, as in life, insults should only be worthy of response if a name is put to them. Anonymous graffiti is not worth the price of freedom of speech.

Ian Monk is founder of Ian Monk Associates and a former executive at the Daily Mail and The Sun.